Various types of plastic container bags utilize a pair of closure strips respectively having male and female members which interlock together to close an open end of the container bags to seal its interior from the external environment. The strips and associated container side walls are typically each formed from thermoplastic material. The container side walls are usually formed by extrusion. A sheet of extruded material is folded, forming two walls, or the two walls are constructed as two separate panels which are then heat sealed together along two or three edges to define the container and an open end along one side thereof. The closure strips are also usually formed by extrusion and then connected to the side walls of the container along the open end by heat sealing or other suitable means to define what is known as a reclosable profile.
Each closure strip is preferably coextruded with a web member which is heat sealed or otherwise secured to one of the side walls of the container body. More specifically a first web generally has an extruded layer formed with an upper web portion and a lower web portion extending coextensive with a first closure strip thereon. This closure strip contains a first locking member projecting inwardly from an inner surface of the first web between upper and lower web portions, to matingly engage a second locking member defining a second closure strip which is coextruded with a second web also having an upper web portion and a lower web portion. The first and second locking members are either male or female, respectively, to mate with each other, and form a sealing device known as a zipper. The lower web portions are heat sealed to the upper edge of respective ones of the plastic side walls as is known. The upper web portions project upwardly from their associated closure strips to respectively define what are commonly known as a top or consumer side web located between the reclosable profile and the open end of the container. Typically, these webs, also known as flanges, are formed to allow for finger gripping to enable the consumer to grasp both side walls and enable separation of the side walls by pulling them away from each other to facilitate unlocking of the zipper.
It has become increasingly desirable to provide reclosable plastic bags with color indicators for locating and closing the zipper. Many customers in the reclosable plastic bag market are looking to various forms of color and graphics to assist with functional and aesthetic purposes in the bag making process. Existing technology in this area typically provides an extruded color line behind, in, above or below the locking members forming the zipper or within the upper and lower webs. This color line can be costly due to the need for a separate extrusion blend to introduce the line. In addition, the color line cannot be intermittent, or be in the form of a logo or printed message because of current manufacturing limitations. Color lines are normally provided through a second layer extrusion done either within the dye or after in a post extrusion fashion.
It is desirable to enhance plastic bag manufacturing using known color indicators by providing the webs with the direct and automatic printing of a color line in the vicinity of the zipper to add flexibility, cost reduction and the ability to offer value added features. Such features include assisting in the identification of source and/or product, and enabling a plastic bag user to more efficiently locate and close the zipper. Such improvements include being able to produce more than one color in a single line of printing, printing logos, customer names or other identification on the zipper and printing intermittently. The color line should also be able to create various graphics and design patterns such as waves and dots in raised or recessed areas and to provide holographic printing, tattoo, photos and picture transfer and the like.